Java JSCEP中的InvalidContentTypeException

我使用在上发布的代码 响应client.enrol，我得到：

InvalidContentTypeException:应为[application/x-x509-ca-cert，application/x-x509-ca-ra-cert]，但为空

URL url = new URL("http://212.29.229.154/certsrv/mscep/mscep.dll");
// Default Callback Mechanism
CertificateVerifier verifier = new ConsoleCertificateVerifier();
CallbackHandler handler = new DefaultCallbackHandler(verifier);

// Creating the Client
 Client client = new Client(url, handler);

KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
keyGen.initialize(2048);
KeyPair requesterKeyPair = keyGen.genKeyPair();

Capabilities caps = client.getCaCapabilities();
String sigAlg = caps.getStrongestSignatureAlgorithm();

X500Principal requesterIssuer = new X500Principal("CN=jscep.org, L=Netanya, ST=Sharon, C=IL");
BigInteger serial = BigInteger.ONE;
Calendar calendar = Calendar.getInstance();
calendar.add(Calendar.DATE, -1); // yesterday
Date notBefore = calendar.getTime();
calendar.add(Calendar.DATE, +2); // tomorrow
Date notAfter = calendar.getTime();
X500Principal requesterSubject = new X500Principal("CN=jscep.org, L=Netanya, ST=Sharon, C=IL"); // doesn't need to be the same as issuer
PublicKey requesterPubKey = requesterKeyPair.getPublic(); // from generated key pair
JcaX509v3CertificateBuilder certBuilder = new JcaX509v3CertificateBuilder(requesterIssuer, serial, notBefore, notAfter, requesterSubject, requesterPubKey);

 // Optional extensions
 // certBuilder.addExtension(X509Extension.keyUsage, false, new KeyUsage(KeyUsage.digitalSignature));

// Signing
PrivateKey requesterPrivKey = requesterKeyPair.getPrivate(); // from generated key pair
JcaContentSignerBuilder certSignerBuilder = new JcaContentSignerBuilder(sigAlg); // from above
ContentSigner certSigner = certSignerBuilder.build(requesterPrivKey);

X509CertificateHolder certHolder = certBuilder.build(certSigner);

JcaX509CertificateConverter converter = new JcaX509CertificateConverter();
X509Certificate requesterCert = converter.getCertificate(certHolder);

KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
keyPairGenerator.initialize(2048);
KeyPair entityKeyPair = keyPairGenerator.genKeyPair();

X500Principal entitySubject = requesterSubject; // use the same subject as the self-signed certificate
PublicKey entityPubKey = entityKeyPair.getPublic();
PKCS10CertificationRequestBuilder csrBuilder = new JcaPKCS10CertificationRequestBuilder(entitySubject, entityPubKey);

DERPrintableString password = new DERPrintableString("password");
csrBuilder.addAttribute(PKCSObjectIdentifiers.pkcs_9_at_challengePassword, password);

PrivateKey entityPrivKey = entityKeyPair.getPrivate();
JcaContentSignerBuilder csrSignerBuilder = new JcaContentSignerBuilder("SHA1withRSA");
ContentSigner csrSigner = csrSignerBuilder.build(entityPrivKey);
PKCS10CertificationRequest csr = csrBuilder.build(csrSigner);

EnrollmentResponse res = client.enrol(requesterCert, requesterPrivKey, csr);